Queensland can use geothermal desalination says study

Queensland, Australia, has ample geothermal energy resources to power thermal desalination plants and provide clean water for small towns suffering from water shortages, according to The University of Queensland’s Queensland Geothermal Energy Centre of Excellence.

“This may not be the solution for large-scale desalination needed for cities like Brisbane, but should have a significant contribution in smaller towns like Dalby and Maleny, which have recently experienced extreme water shortages,” said centre director Professor Hal Gurgenci on 7 December 2009. “Overseas experience suggests that these systems can be scaled up to provide 10-20 m³/d of water, while also helping greenhouse plant growing.”

Queensland’s geothermal resources range from high-temperature hot fractured rock (HFR) of the Cooper, Eromanga and possibly Drummond basins to hot sedimentary aquifiers (HSA) of the Great Artesian basin. Prof Gurgenci said that while some of these resources may not be hot enough for electricity generation, they would be a perfect fit for thermal desalination of underground brackish aquifers.

“Australian emphasis so far has been on large-scale desalination using reverse-osmosis (RO) technology although an overwhelming fraction of desalination around the whole is done by thermal means,” Prof Gurgenci said.

“Studies indicate that for plants in the range of 1,000-100,000 m³/d, thermal desalination technologies are more suitable than RO, especially if there is a cheap and abundant supply of heat,” he revealed. “A geothermal-powered desalination plant in that range can easily provide the entire fresh water needs for an outback city at the cost of around Aus$0.8-1.60 per kilolitre (US$ 0.73-1.46/m³).”

The estimated cost developed by the Centre’s researchers significantly undercuts the 2010/2011 bulk water prices of Aus$ 1.00-2.00/m³ outlined by the Queensland Water Commission.

Prof Gurgenci said the technology could also be used in smaller-scale applications, and in particular in agricultural settings.

“Geothermal heat can be used to heat and humidify a greenhouse and produce fresh water at the same time,” he explained. “This is a clever combination where desalination is coupled with an agricultural function which is both cost-efficient and environmentally-friendly.”

The Queensland Geothermal Energy Centre of Excellence is funded by the Renewable Energy Fund and the Climate Change Fund established as part of Queensland’s ClimateSmart 2050 climate change strategy.